<template>
  <div class="nav-bar" :class="{'is_fixed':isFixed}">
    <div class="container">
      <div class="pro-title">{{title}}</div>
      <div class="pro-param">
        <a href>概述</a>
        <span>|</span>
        <a href>参数</a>
        <span>|</span>
        <a href>用户评价</a>
        <slot name="buy"></slot>
      </div>
    </div>
  </div>
</template>
<script>
export default {
  name: "nav-bar",
  props:{
    title:String
  },
  data() {
    return {
      isFixed: false
    };
  },
  mounted() {
    window.addEventListener("scroll", this.initHeight);
  },
  methods: {
    initHeight() {
      let scrollTop =
        window.pageYOffset ||
        document.documentElement.scrollTop ||
        document.body.scrollTop;
      this.isFixed = scrollTop > 152 ? true : false;
    },
    // 节约性能组件移除的时候取消事件
    destroyed() {
      window.removeEventListener('scroll',this.initHeight,false)
    },
  }
};
</script>
<style lang="less">
.nav-bar {
  height: 70px;
  line-height: 70px;
  border-top: 1px solid @colorH;
  background-color: #fff;
  z-index: 10;
  &.is_fixed {
    position: fixed;
    top: 0;
    width: 100%;
     box-shadow: 0 5px 5px @colorE;
  }
  .container {
    .flex-nowrap-sb;
  }
  .pro-title {
    font-size: @fontH;
    color: @colorB;
    font-weight: bold;
  }
  .pro-param {
    font-size: @fontJ;
    span {
      margin: 0 10px;
    }
    a {
      color: @colorC;
    }
  }
}
</style>